What is the meaning of the Prophet's (peace and blessings be upon him) saying: "And whoever goes out for the forenoon glorification, none but He [Allah] establishes him," and does this mean going out to the mosque to perform the Duha prayer, or does it include performing it anywhere?

The mosque is not a condition for the Duha prayer; rather, it is like other supererogatory prayers that can be performed at home. It has not been authentically reported that the Prophet (peace be upon him) specifically intended to go to the mosque to perform it. The hadith, "Whoever goes out for the Duha glorification [prayer]… his reward is like that of one performing 'Umrah," has been deemed hasan (good) by some scholars, and it might be understood to imply the superiority of going out for it. However, it contradicts the hadiths that prefer supererogatory prayers to be performed at home, such as his (peace be upon him) saying, "Indeed, the best prayer of a person is in his home, except for the obligatory prayer." Some scholars have interpreted the hadith about Duha prayer as referring to those who cannot perform supererogatory prayers in their usual place, such as merchants in the market, meaning that they leave their work and go out to pray it.